• Journal of Korean Society of Forest Science
• /
• v.85 no.1
• /
• pp.120-129
• /
• 1996

This study was carried out to investigate the hydraulic architecture such as relative hydraulic conductivity, Leaf specific conductivity(LSC), Huber value, Specific conductivity of the stem, branch and Junctions of stem-to-branch in Quercus mongolica trees. The hydraulic architecture of various hydraulic conductivities of stem and branch was described. The results obtained were summarized as follows : 1. The range of relative hydraulic conductivity was $2.5526{\times}10^{-12}$ to $1.2260{\times}10^{-10}m^2$ in stems, $1.6279{\times}10^{-11}$ to $6.8378{\times}10^{-11}m^2$ in branches. The relative hydraulic conductivities increased with decreasing diameter of stem and branch. The relative hydraulic conductivity of one-year-old terminal shoots were two times greater than that of the lateral shoots. 2. LSC value was larger at the top than at the base in stem. LSC is much smaller in branches than in stem ; especially smallest at branching part. 3. Hydraulic conductivities of the branching part appeared the different values with the 4 type and 4 type. Relative hydraulic conductivity, LSC, Specific conductivity and mean vessel diameter in type branching part were larger in stem than in branch part, but not found in the branching part of Y type. 4. LSC and Specific conductivity of stem increased with decreasing diameter, but Huber value slowly increased with decreasing diameter ; especially highest at less than 1cm diameter. 5. LSC, Huber value, and mean diameter of vessels were larger at 1-year-old leader shoots than at lateral shoots. 6. The mean vessel diameter in various parts of a tree decreased with decreasing diameter of stem, but the number of vessels per unit area($mm^{-2}$) increased reversely. Mean vessel diameter in stem decreased sharply at earlywood and slowly at latewood with decreasing diameter of stem.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2008.10a
• /
• pp.498-507
• /
• 2008

The mixture of bentonite powder and water is generally used to maintain the stability of excavation surface during the construction of vertical cutoff walls. The filter cake on the sidewall surface is the result of filtration of slurry into the adjacent soil formation. The filter cake is believed to have a very low hydraulic conductivity compared to that of the cutoff wall. This paper evaluates hydraulic conductivities of bentonite filter cakes set up with three types of bentonites under various pressure levels. A modified fluid loss test was employed in this experiment. Theory of filtration process was reviewed to explain the procedure in the present experiment. Hydraulic conductivity of the filter cakes with consideration of the filter medium resistance was evaluated. The results of the experiment with two calculation methods and discussion are presented to show the efficiency of the modified fluid loss test.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2008.10a
• /
• pp.1502-1511
• /
• 2008

The mixture of bentonite powder and water is generally used to maintain the stability of excavation surface during the construction of vertical cutoff walls. The filter cake on the sidewall surface is the result of filtration of slurry into the adjacent soil formation. The filter cake is believed to have a very low hydraulic conductivity compared to that of the cutoff wall. This paper evaluates hydraulic conductivities of bentonite filter cakes set up with three types of bentonites under various pressure levels. A modified fluid loss test was employed in this experiment. Theory of filtration process was reviewed to explain the procedure in the present experiment. Hydraulic conductivity of the filter cakes with consideration of the filter medium resistance was evaluated. The results of the experiment with two calculation methods and discussion are presented to show the efficiency of the modified fluid loss test.

• Journal of Soil and Groundwater Environment
• /
• v.22 no.3
• /
• pp.27-41
• /
• 2017

This study dealt with the characteristics and the interrelations of hydrogeological parameters such as hydraulic conductivity, dispersivity and effective porosity of unconsolidated sediments for providing the basic data necessary for the planning of the management and preservation of groundwater quality in the Nakdong River Delta of Busan City, Korea. Groundwater quality in this area has been deteriorated due to seawater intrusion, agricultural fertilizer and pesticide, industrial wastewater, and contaminated river water. The physical properties (grain size distribution, sediment type, sorting) and aquifer parameters (hydraulic conductivity, effective porosity, longitudinal dispersivity) were determined from grain size analysis, laboratory permeability test and column tracer test. Among 36 samples, there were 18 Sand (S), 7 Gravelly Sand (gS), 5 Silty Sand (zS), 5 Muddy Sand (mS), and 1 Sandy Silt (sZ). Hydraulic conductivity was determined through a falling head test, and ranged from $9.2{\times}10^{-5}$ to $2.9{\times}10^{-2}cm/sec$ (0.08 to 25.6 m/day). From breakthrough curves, dispersivity was calculated to be 0.35~3.92 cm. Also, effective porosity and average linear velocity were obtained through the column tracer test, and their values were 0.04~0.46 and 1.06E-04~6.49E-02 cm/sec, respectively. Statistical methods were used to understand the interrelations among aquifer parameters of hydraulic conductivity, effective porosity and dispersivity. The relation between dispersivity and hydraulic conductivity or effective porosity considered the sample length, because dispersivity was affected by experimental scale. The relations between dispersivity and hydraulic conductivity or effective porosity were all in inverse proportion for all long and short samples. The reason was because dispersivity was in inverse proportion to the groundwater velocity in case of steady hydrodynamic dispersion coefficient, and groundwater velocity was in proportion to the hydraulic conductivity or effective porosity. This study also elucidated that longitudinal dispersivity was dependent on the scale of column tracer test, and all hydrogeological parameters were low to high values due to the sand quantity of sediments. It is expected that the hydrogeological parameter data of sediments will be very useful for the planning of groundwater management and preservation in the Nakdong River Delta of Busan City, Korea.

• Korean Journal of Soil Science and Fertilizer
• /
• v.44 no.6
• /
• pp.998-1003
• /
• 2011

This investigation was performed to determine the hydraulic conductivity coefficient and water holding capacity for a specified compaction forces which are the amount of mechanical energy applied to the porous granule (PG) volume. Most current specifications of minerals and perlite as growth media require to be compacted to a specified density, which in general is equivalent to a certain percentage of laboratory compaction. The water holding capacity of the saturated PG was very large at potential above -1 bar compared with perlite, but very little water remained below this value. The water holding capacity and hydraulic conductivity characteristics of graded PG amended with the ground coir less than 2 mm in diameter were also determined from pressure outflow data. The saturated hydraulic conductivity of the saturated and compacted PG was slightly lower by more than one tenth order of magnitude at equal matric potentials of perlite, but when expressed on the basis of equal water deficits, the conductivity of PG was higher at all but the smallest deficits than those of perlite.

• The Journal of Engineering Geology
• /
• v.16 no.1 s.47
• /
• pp.15-21
• /
• 2006

Sandy soils obtained from the field were examined by the way of particle analyses. The hydraulic conductivity values of the disturbed soil samples were measured by the falling head method. Then the correlations between the hydraulic conductivity and particle distribution were defined. The soil which was a product of the weathering of the granitic rocks belonged to sand and loamy sand area in a sand-silt-clay triangular diagram. The measurements of hydraulic conductivity were $1.15X10^{-5}\sim7.31X10^{-4}cm/sec$ which is the range of sand and silt. It was clearly observed that the hydraulic conductivity measurements of the sandy soils showed stronger correlations with the particle variances rather than the mean grain sizes. The larger the variances, the smaller the hydraulic conductivity measurements. The sandy soil which was a product of weathered granite and whose mean grain size was $0.38\sim1.97mm$ showed regression curves of $y=6.0E-5x^{-1.4}$ in a correlations between hydraulic conductivity and particle variances. Accordingly, it is clearly concluded that making estimates with-out any consideration about particle variances can produce serious errors.

• The Journal of Engineering Geology
• /
• v.20 no.2
• /
• pp.203-212
• /
• 2010

The aim in this study is used to develop the remediation technologies for contaminated ground water. Slug, single well pumping and step-drawdown tests have been used to obtain hydraulic parameter estimates in the field. Slug tests yield hydraulic conductivity values using the Bouwer and Rice and C-B-P analysis methods. The mean and median hydraulic conductivity values of Bouwer and Rice method are $4.48{\times}10^{-3}$ and $1.16{\times}10^{-3}cm/sec$, respectively. On the other hand, C-B-P method gave mean and median hydraulic conductivity values of $2.37{\times}10^{-3}$ and $7.09{\times}10^{-4}cm/sec$, respectively. These analyses show a trend for the Bouwer and Rice method to yield lower hydraulic conductivity values in low permeability zones of granite in the study area. Sing well pumping test data were calculated through type curve in GW7, GW12 and MW9 wells. It could be interpreted that the differences of hydraulic conductivity and transmissivity values between GW7 and GW12, MW9 is related with fault clays and fractures in the bedrock among the wells. Step-drawdown tests were carried out in the KDPW1 and KDPW2 wells. The hydraulic parameter of KDPW1 and KDPW2 showed very litter difference between the values. The study of hydraulic parameter estimates can be used to purify in contaminated groundwater.

• The Journal of Engineering Geology
• /
• v.27 no.4
• /
• pp.377-382
• /
• 2017

Field experiments were conducted to estimate streambed hydraulic conductivity at 15 sites in the Anseongcheon watershed, Korea. Seepage meters and piezometers were installed in the streambed at each site to measure the amount of stream water-groundwater exchange and the hydraulic gradient. The vertical hydraulic conductivity was then calculated using Darcy's formula. The measured stream water-groundwater exchange rates were $4.08{\times}10^{-6}$ to $1.49{\times}10^{-5}m/s$, and the vertical hydraulic gradients were 0.005 to 0.145. The data suggest the streambed hydraulic conductivity to be $7.80{\times}10^{-5}$ to $1.58{\times}10^{-3}m/s$. The results show significant differences in connectivity between stream and aquifer. Quantification of the hydraulic interconnection between stream and aquifer, and evaluation of the effects of groundwater development and utilization on the streamflow require hydrogeological investigations of the connection between stream and aquifer, including the hydraulic conductivity of the streambed. Various field testing and analysis methods for hydrogeological assessment also require further improvement.

• Proceedings of the Korean Geotechical Society Conference
• /
• 1998.03a
• /
• pp.307-314
• /
• 1998

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2004.04a
• /
• pp.341-345
• /
• 2004

An attempt has been made in this study to evaluate an applicability of Relative Effective Porosity Model (REPM) as a method for estimating saturated hydraulic conductivity (K$_{s}$) for homogeneous coarse, medium, and fine sands. The saturated hydraulic conductivities obtained from REPM are converted into average linear velocities using Darcy's Law and compared with the results from experimental tracer tests for homogeneous coarse, medium, and fine sand layer. Two types of tracer tests analyses, analytical solution using CXTFIT and moment methods, are performed to obtain reasonable linear velocity range for each layer. For the coarse and medium sands, the converted average linear velocity from REPM is in the velocity range obtained from tracer tests. However, small difference between the results from REPM and tracer tests is found for the fine sands. These results show that REPM gives reasonable estimates of saturated hydraulic conductivity.y.